Multifunctional Conductive Polymer Modification for Efficient CO₂ Electroreduction in Acidic Electrolyte

Abstract Electrode‐electrolyte interfacial modification by hydrophobic molecules represents a promising strategy for suppressing competing proton reduction in acidic electrocatalytic carbon dioxide reduction reactions (CO 2 RR), meanwhile sacrificing extra overpotential due to increased ohmic resistance. Herein, a multifunctional conductive polymer, polyaniline modified by p‐aminobenzenesulfonic acid (ABSA‐polyaniline), is constructed between Cu catalyst layer and electrolyte to simultaneously create an ideal microenvironment for CO 2 RR and enhance the charge transfer and ion transport processes at the electrochemical reaction interface. This polymer layer balances the local hydrophobicity, promotes CO 2 adsorption and activation, and regulates the mass transport of K + , H + , and OH − ions, thus significantly enhancing the CO 2 RR kinetics in acidic medium, yielding a high Faraday efficiency (FE = 81%) for multicarbon products at 600 mA cm −2 . More importantly, compared with commonly used hydrophobic molecules, the conductive nature of ABSA‐PANI helps to reduce the ohmic resistance of the electrode, leading to notably lowered cathode overpotential at industrial‐grade current density and improve cathode energy efficiency over a wide potential window. This work sheds light on the development of highly efficient acidic CO 2 RR systems, especially for those with low alkali cation concentrations and low CO 2 concentrations.